METHOD FOR THE CONTACTLESS DETECTION OF THE POSITION OF A BUTTERFLY-VALVE SHAFT OF A BUTTERFLY-VALVE CONNECTING PIECE AND A BUTTERFLY-VALVE CONNECTING PIECE

摘要

The invention relates to a method for the contactless detection of the position of a butterfly-valve shaft (18) of a butterfly-valve connecting piece (10), said butterfly-valve shaft (18) being driven by an electric actuator (30) and having a magnet (34) at one end (36), which is aligned in a contactless manner with a sensor (40) that is located on a cover (50). The aim of the invention is to reliably guarantee the detection of the position of the butterfly-valve shaft (18), even over particularly long periods of time, using a contactless position detection device (32). To achieve this, the sensor (40) has a first and a second magnetoresistive sensor element (52 and 54), an approximately sinusoidal signal (S1) being generated in the first sensor element (52) and an approximately cosinusoidal signal (S2) being generated in the second sensor element (54) by means of the magnet (34), during the rotation of the butterfly-valve shaft (18). According to the method, an approximately arc tangential signal (P) is generated in the butterfly-valve connecting piece (10) from the signal (S1) and the signal (S2) and a control signal (C) is generated, based on said approximately arc tangential signal (P). The control signal (C) is fed to the actuator (30, 130) that is located in the butterfly-valve connecting piece (10, 100), to adjust the position of the butterfly-valve shaft (18, 118).